RESUMO
OBJECTIVE: To examine the impact of important weight loss on insulin inhibition of its own secretion during experimentally induced hyperinsulinemia under euglycemic conditions. DESIGN: Longitudinal, clinical intervention study--bariatric surgery (vertical banded gastroplasty--gastric bypass--Capella technique), re-evaluation after 4 and 14 months. SUBJECTS: Nine obese patients class III (BMI=54.6+/-2.6 kg/m2) and nine lean subjects (BMI=22.7+/-0.7 kg/m2). MEASUREMENTS: Euglycemic hyperinsulinemic clamp (insulin infusion: 40 mU/min m2), C-peptide plasma levels, electrical bioimpedance methodology, and oral glucose tolerance test (OGTT). RESULTS: BMI was reduced in the follow-up: 44.5+/-2.2 and 33.9+/-1.5 kg/m2 at 4 and 14 months. Insulin-induced glucose uptake was markedly reduced in obese patients (19.5+/-1.9 micromol/min kg FFM) and improved with weight loss, but in the third study, it was still lower than that observed in controls (35.9+/-4.0 vs 52.9+/-2.2 micromol/min kg FFM). Insulin-induced inhibition of its own secretion was blunted in obese patients (19.9+/-5.7%, relative to fasting values), and completely reversed to values similar to that of lean ones in the second and third studies (-60.8+/-4.2 and -54.0+/-6.1%, respectively). CONCLUSION: Weight loss in severe obesity improved insulin-induced glucose uptake, and completely normalized the insulin inhibition on its own secretion.